1. Field of the Invention
The present invention relates to printing apparatuses and printing systems.
2. Description of the Related Art
Some printing apparatuses for printing images on a medium have an element to which a plurality of drive signals can be applied. For example, there has been proposed a printing apparatus in which a plurality of types of drive pulses for causing ejection of different amounts of ink are divided into two and contained in two drive signals and the drive pulses to be applied to a piezo element are selected (e.g., see Japanese Laid-Open Patent Publication No. 2000-52570). There has also been proposed a printing apparatus in which a drive pulse that is necessary in forming the largest dot is contained in one drive signal and drive pulses that are necessary in forming other dots are contained in another drive signal (e.g., see Japanese Laid-Open Patent Publication No. 2003-246086).
However, neither of the above-mentioned printing apparatuses gives consideration to cases in which a plurality of drive signals are simultaneously applied to the element. For example, in a configuration in which the number of switches for controlling the application of drive signals is the same as the number of the drive signals and the switches are turned on or off by an actuating signal outputted through a signal line, noise may be applied to the switches through this signal line. In cases where the noise applied to the switches is at a level equal to or above the operating voltage of the switches, the switches may be turned on. Here, when a certain switch has been turned on by an actuating signal for actuating that switch, if another switch is turned on due to the noise, then two drive signals will simultaneously be applied to the piezo element. In such a case, failures such as unexpected operation of the piezo element may occur.